This invention relates generally to photodetection apparatus and more particularly to means for providing such apparatus with acuity regarding relatively long wavelength light.
Sensitivity, that is, the ability to develop useful information from weak signals, is a desirable characteristic of photodetectors, particularly those of the image-forming type. However, the photodetectors of the prior art display decreasing spectral sensitivity at regions away from the wavelength of peak spectral sensitivity. An example of this is found in military night vision equipment which can sense and provide an image of a target weakly illuminated by ambient or by a conventional infrared searchlight but which cannot "see," or may even be damaged by, incident infrared laser light.
It is therefore an important object of this invention to provide photodetection apparatus which is highly sensitive to a given, narrow band of electromagnetic radiation but which is capable of providing useful information regarding one or more spectrally different radiations.
A more general object of the invention is to provide new and improved photodetection apparatus.
A more specific object of the invention is to provide night vision equipment having laser sensitivity.
These and other objects and features of the invention will become more apparent from a consideration of the following descriptions.